1. Field of the Invention
The present invention relates to semiconductor devices, and more particularly, to a method for fabricating a semiconductor device having a MIM capacitor including an uneven surface over a large area.
2. Discussion of the Related Art
The capacitor of a semiconductor device may have a poly-insulator-poly (PIP) or metal-insulator-metal (MIM) structure.
Along with the increasing demand for highly integrated multi-function devices, there is an increasing requirement for a high-capacitance capacitor. To increase a capacitance in the capacitor, the capacitor may be formed by using a material having a greater dielectric constant, by decreasing the thickness of an insulating layer, or by increasing a surface area of the capacitor. There are limitations, however, with respect to using a material having a greater dielectric constant and decreasing the thickness of an insulating layer.
As shown in FIG. 1, illustrating a method for forming a capacitor of a semiconductor device according to the related art, an insulator 20 of Si3N4 is formed on a lower metal layer 10 by plasma-enhanced chemical vapor deposition. Subsequently, an upper metal layer 30 of Al/Ti/TiN is deposited and patterned on the insulator 20, thereby forming a MIM structure. After forming a lower metal pattern, an insulating layer 40 is formed by a high-density plasma deposition.
In the method according to the related art, widely used methods for improving the capacitance include applying new materials and developing layer characteristics. However, the capacitor has a flat surface. Thus, increasing integration is limited. Furthermore, the improvement of capacitance in the capacitor is limited.